Electron discharge device



May 2, 1933. v. L. RONCI ELECTRON DISCHARGE DEVICE Filed Spt. so. 1929//vl E/V7'0R V. L. Ro/vc/ BY Okoitvu 7M ATTORNEY Patented May 2, 1933UNITED STATES PATENT OFFICE.

VICTOR L. BONCI, OF BROOKLYN, NEW YORK, ASSIGNOR TO BELL TELEPHONE LABO-RATORIES, INCORPORATE), OF NEW YORK, N. Y., A CORPORATION OF NEW -YOBKnnndrnon mscmnsn nnvrcn Application filed September 80, 1929. Serial No.396,034.

This invention relates to electron discharge devices and moreparticularly to such creasing the power output have been in general usein long wave transmission systems and usually consist of a cup-shapedanode forming a part of theenclosing vessel and a glass portion whichsupports the cathode and grid in spaced relation with respect to theanode. This construction has proved efiicient and satisfactory withinthe range of frequencies usually employed in long wave systems, such asbroadcasting and transoceanic radio telephony. However, in short wavetransmission systems the intensive and concentrated high tension, highfrequency current, applied to the control electrode or grid creates afield which readily melts the glass vessel and therefore causes failureor else causes heating of the filament seals and consequent rupturewhich destroys the vacuum.

In accordance with this invention, these difliculties are overcome bysupporting the grid from the opposite end of the anode with respect tothe cathode. In this construction a tubular metallic anode open at bothends is provided with glass portionswhich are sealed to the openends ofthe anode. A filament assembly is sealed into one of the glass portionsand extends into the anode. The glass portion on the other end of theanode is provided with a coaxial tubular metallic termination which isdirectly in contact with a cylindrical supporting structure whichcarries the grid electrode at its inner end, the grid being locatedbetween the filament and the wall of the tubular anode. Thisconstruction materially reduces the establishment of inju-' as a. largesurface area to apply the high frequency energy to the grid electrode.

One feature of the invention relates to providing a metallic shieldaround the glass stem which encloses the filament seals andmaintainingthis shield at the same potential as the filament. This isaccomplished by rigidly supporting the filament structure concentricallyfrom the inner end of the stem and sealing the filament leading-in wireswithin the stem to metallic cups which are fused to the stem. A metallicshield encircles the stem over a distance determined by the length ofthe metallic cup seals and the shield is electrically connected to thefilament support, to eliminate electrical charges building up on theglass surface.

Another feature relates to the filament supporting structure and thearrangement for evacuating the complete device through a glasstubulation which communicates with the vessel through apertures formedby p'ortions of the filament supporting structure. This structurecomprises a glass stem terminating in a tubular opening to which issealed a metallic reinforcing collar and which connects with an externalglass sealing extension projecting toward the outer end 'of the glassportion. A filament structure having a soild plug at one end is rigidlysecured in the reinforcing collar, the plug having ferrules which formcommunicating paths between the sealing extensions and the interior ofthe discharge device.

These and other features of the invention will be clearly understoodfrom the following detailed description in connection with theaccompanying drawing in which:

Fig. 1 illustrates a high power discharge device made in accordance withthis invention having the enclosing vessel in crosssection to show thedetail construction.

Fig. 2 is an enlarged view of the filament end of the device of Fig. 1shown largely in cross-section and with portions broken'away to clearlyshow the construction.

Fig. 3 is an enlarged detail view of the other end of the device of Fig.1, shown in cross-section to illustrate'the assembly of the improvedelectrode support.

Fig. 4 is a rear ersp'ective view showing sections of the fi amentsupporting structure and the detail construction of the parts enteringinto the assembly.

Fig. 5 is an enlarged detail view partly in cross-section of theconnectors for conpliig the filament to the leading-in wires, an

Fig. 6 is a perspective view of a portion of a filament and supporttherefor, representing a modification of the filament and support shownin Fig. 1.

eferring to the drawing the electron discharge devlce of this inventioncomprises a highly evacuated enclosing vessel having a tubular metallicportion or anode 10, preferably of copper, and open at both ends towhich are attached glass end portions 11 and 12. The open ends of thetubular anode portion 10 are tapered outwardly and reduced in thicknesstowards the edge to a knife edge and sealed, fused or welded to theglass portion as shown at 13 in accordance with a method disclosed in W.G. Houskeeper Patent 1,294,466, February 18, 1919.

Since excessive heat is generated during the o eration of-the device,this heat-is conveye away from the glass-to-metal seal as shown at 13 bya funnel-shaped shield 14 which extends over the area of the seal and issecured to the inner surface of the anode portion 10. Similarly, inorder to dissipate the heat generated in the device, a cooling mediummaybe circulated around the exterior of the anode 10 and'this isaccomplished by surrounding the anode with a. container or jacket (notshown) through which the cooling medium may be circulated. As shown inFig. l, annular flanges 15 are secured to the wall of the tubular anodeto form the ends of the container which may be of a form shown in U. S.Patent 1,628,999, May 17, 1927. The glass portion 11 is provided with aninwardly projecting stem 16 havin a central tubular extension 17 whichis joined to a glass tubulation reentrant with respect to the stem. Theglass stem 16 is also provided with two reentrant' tubular extensions19' and 20 which are arranged on opposite sides of the tubulation 18 andextend parallel therewith. Attached to the central extension 17 is ametallic reinforcing collar or sleeve 21 which is sealed to theextension 17 in the same manner as the seal between the glass portionsof the enclosing vessel and the tubular anode and shown more clearly inFig. 2 at 22. The tubular extensions 19 and 20 are closed by metalliccaps 23 and 24 by a similar glass-to-metal sea-l as disclosed in theHouskeeper patent mentioned above.

The filament structure comprises a central upright metallic rod 25 whichis provided with a solid metallic plug 26 at one end having longitudinalcut-out portions 27 and 28, the metallic plug 26 havin a diameter toeasily fit within the meta ic collar 21 and secured therein by screwswhich pass through the collar and plug. This construction forms a rigidsupport within the device and the cut-out portions of the plug 26 andthe wall of the collar 21 form communicating passage-ways between theinterior of the ent1re vessel and the glass tubulation 18, whereby thedevice can easily be evacuated and all gases removed to secure a highvacuum. The upright supporting rod 25 carries at its free end a pair ofmetallic nests 29 which support insulators having hooks to engage thebights of the filament 30. These nests and the associated parts of thestructure may be similar to the insulating supports disclosed in Patent1,616,139, February 1, 1927. The filament 30, preferably of tungsten, isformed into an M with the bights strung-over the hooks supported in thenests 29, the bight at the lower end being strung on a hook 25a carriedby the upright rod 25 and the free ends attached to metallic connectorssupported on a metallic disc carried by the up right rod 25. Theconstruction of the connectors is shown more in detail in Fi 5 in whichthe metallic disc 31 is provlded with two openings located on oppositesides of the central support 25. Extending through each aperture is athreaded metallic rod 32 having a metallic shoulder 33 thread ed on therod and positioned between the ends thereof. This shoulder engagesaflanged insulating collar or eyelet 34 which is seated in the apertureof the metallic disc 31 on one surface and through which the metallicrod 32 extends beyond the lower surface thereof. A similar flangedinsulating collar or eyelet 35 engages the other surface of the disc 31and is seated in the aperture. The complete assembly is rigidly securedin place by a metallic sleeve 36 which is threaded on the metallic rod32 and rigidly fastens the insulating collars 34 and 35 against themetallic disc 31. The free ends of the filament 30 are attached to theslotted connector rod 32 by a wire helix which is spot welded to preventloose connection between the filament and connector. The hollow metallicsleeve 36 on the opposite end of the connector forms a cavity for aleading-in wire 37 which is joined to the metallic cups 23 and 24. Theleading-in wire 37 is provided with a flexible braid portion 38 tocompensate for expansion and constraction during operation. Thehermetically sealed cups or seals 23 and 24 are provided with conductorextensions which are attached to terminals 39 carried by a metallic base40 substantially enclosing the end of the glass portion 11.

In order to increase the insulating ath between the low potentialterminals of the filament and the high tension, high frequency terminalof the control electrode or grid when employing the discharge device inshort wave transmission work, the grid electrode is supported from theopposite end of the device as shown in the drawing. The electrodeextends from and is supported by the glass portion 12'which is sealed tothe other end of the metallic anode 10. The glass portion 12 is providedwith an inwardly projecting stem 41 having an outwardly extendingtapered portion 42 which is sealed to a metallic thimble or cup-shapedtermination 43. The cup-shaped termination 43 is provided with a taperedknife-edge which is fused or welded to the glass portion 42 in a mannerheretofore described. The cup-shaped termination 43 is coaxiallypositioned with respect to the glass ortion 12 and the anode 10 andpro]ects eyond the end of the glass portion 12 to serve as a largesurface terminal for a urpose to be hereinafter described. Extendinginto the'cup-shaped termination 43 is a cylindrical conductor or tubularmetallic sleeve member 44 having its end formed to fit accurately in theend of the metallic termination 43 and provided with spaced integralannular rings 45 and 46 having a diameter substantially the same as theinner diameter of the metallic termination 43. These rings serve aspositioning means for the tubular conductor 44 and form shoulders forseveral turns of cold solder as shown at 47 which may be heatedexternally to fuse the solder and mechanically join the tubularconductor 44 to the inner surface of the metallic termination 43.

The tubular conductor 44 is also provided with a plurality of spacedholes or vents 48 in order to remove air and gases from the spacebetween the walls of the tubular memher or conductor 44 of the metallictermination 43. The free end of the tubular conductor 44 is providedwith raised extensions or ridges 49 at distributed points to serve assleeves for the upright wires 50 upon which the grid helix 51 is wound.The extentions 49 are crimped around the wires 50 and securely maintainthem in rigid position. The upper ends of the wires 50 are surrounded bya metallic band 51 to maintain the wires in parallel relation and toform a more rigid structure. The tubular structure of the grid supportforms a large surface area for supplying the high frequency, hightension energy to the grid or control electrode positioned between thefilament and anode of the discharge device and the unitary assembly ofthe grid, holl ow tubular member 44 and the metallic terminal 43 servesas a means for accurately positioning the grid electrode in coaxialrelation with respect to the filament and anode.

The large current supplied to the filament by the leading-in wires has atendency to build up destructive electrical char es on the glass stemthrough which the le in -in wires are sealed and these charges 0 onfracture the glass due to the intensive heating. In accordance with thisinvention these charges are deflected by surrounding the glass'stemthrough which the leading-in in seals with a metallic shield or collar53 which is prevented from slippin on the smooth glass by a wire screen52 w ich presents a rough surface to the glass. The

shield 53 extends over an area of the glass stem substantially thelength ofthe metallic cup seals 23 and 24 enclosed within the stem andthis shield is electrically connected to the metallic sleeve 21 by aplurality of straps 54 so that the shield 53 is maintained at the samepotential as the filament and any charges tending to creep over theglass surface of the stem will encounter the shield 53 and be conductedto the filament supportwhere they are dissipated.

The length of filament employed in the device shown in Fig. 1 requires asufiiciently rigid supporting arrangement to maintain the length offilament in accurate relation with respect to the other electrodes.However, when a shorter length of filament is desired, for instance, ina device of less power, the filament may be formed as shown in Fig, 6,in which the filament 55 is formed into an inverted U and positioned ina slit in the upper end of upright member 56. After the filament issecured in .the end of the upright member 56- the slit may be closed byfusing the end of the rod by welding.

While the invention has been disclosed in the particular embodiment, itis of course understood that various modifications may be made in thedetailed parts of the device without departing from the scope of theinvention as defined in the appended claims.

What is claimed is:

1. An electron discharge device comprising an enclosing vessel having aglass portion and a metallic portion, said metallic portion forming ananode of said device, said glass portion having an inwardly projectingstem and a central protruding tubulation, a metallic collar attached tosaid stem at the inner end of said tubulation, an electrode supportedfrom said collar and extending into said anode, and means supportedwithin said collar having a passageway between said tubulation and theinterior of said vessel.

2. An electron discharge device comprising an enclosing vessel having aglass portion and a metallic portion, said metallic portion forming ananode of said device, said glass portion having an inwardly prolation, ametallic collar attached to said stem at the inner end of said'tubul'ation, a metallic lug having cut-out portions'surrounded y saidcollar, an upright support 5 extending from said plug, and an electrodecarried by said support.

3. An electron discharge device comprising an enclosingvessel having aglass portion and a metallic anode portion, said glass 10 portion havingan inwardly projecting stem, an electrode supported from said stem andextending into said metallic portion, a pair of metallic cup memberssealed to said stem and located therein, connections from said 1;electrod to said metallic members, and a metallic shield surroundingsaid stem over a distance determined by the length of said metallicmembers and electrically connected to said electrode. v

4. An electron discharge device comprising an enclosing vessel having aglass portion and a metallic anode portion, said glass portion having aninwardly projecting stem,

an electrode supported from said stem and extending into said metallicportion, a pair of cup-shaped terminals sealed to said stem andsubstantially enclosed thereby, leadingin wires for said electrodeattached to said terminals, a metallic shield engaging said 3 stem overan area enclosing said terminals,

and a plurality of metallic strips connecting said shield to saidelectrode.

5. An electron discharge device comprising a vessel having a glassportion and a metallic anode portion, a metallic upright memberextending into said anode portion, an apertured metallic disc securedthereto between the ends, a metallic connector extending through saiddisc having 40 'a shoulder on one side, a metallic sleeve member on theother side of said disc engaging said connector, an insulator on eachside of said disc rigidly fastened thereto by said connector and sleevemember, a filament car- I 45 ried by said connector and upright member,and a conductor attached to said connector by said sleeve member.

6. A double ended high power discharge device comprising a metallicportion form- 5' ing the anode of the device and a glass portion at eachend thereof, a filament within said anode portion, an inwardlyprojecting stem on one glass portion supporting said filament, aninwardly projecting stem on the '55 other glass portion, a projectingmetallic hollow terminal coaxially positioned with respect to said anodeportion and attached to said second stem, a grid spaced between saidanode and filament, and a tubular conductor "support-ing said grid andseated in said hollow terminal.

T In witness whereof, I hereunto subscribe my name this 28th day ofSeptember 1929.

' VICTOR L. RONCI.

